In the context of everyday life and due to the mobility of persons and objects, the desirability has increased to lock places and objects for preventing unauthorized access to, employment or removal thereof.
Such is the case, for example, the leisure time sporting goods articles, such as skis, sailboards, bicycles, canoes, etc. These articles are often transported on the roofs of motor vehicles, being fixed to a transporter system (commonly known as "load carriers") having a framework including a combination of feet and bars. Examples of such transporter systems are boat carriers, luggage carriers, box load carriers, ski racks and roofracks. For reasons of security, when utilizing such transporter systems it is advantageous to lock both the objects being transported, as well as the transporter system, with locks that are uncumbersome and reliable.
Such is also the case, for example, in the automotive field, with caravans or boats where wheels, gas caps, knobs, deflectors, outboard motors etc. are advantageously locked. If the case arises, such locks can be in the form of individual locking cables.
Comparable applications are also currently found where apartments, security apparatuses, shared industrial installations, office furnishings, etc., are involved. In many of these cases, locks having housings, barrels and sliding tumblers are used for locking, thereby restricting access thereto, and utilization thereof, to authorized persons.
A considerable inconvenience of these systems results from the requirement that, for each individual lock used, a respective key is needed that is matched thereto. In cases where several locks are utilized (such as with the racks and carriers noted above), this results in the user having to carry and maintain numerous keys. Unfortunately, such keys are readily susceptible to being lost. Also, the provision of several keys presents the user with problems of choosing the correct key for each lock, so that often several different keys have to be tried before the correct key is located.
Alternatively, to avoid the inconveniences posed by the necessity of using a plurality of keys, a combination of locks are sometimes employed that function (are locked and unlocked) with a sole, common key.
Finally, in order to provide flexibility in systems utilizing a common key and to permit one or more of the individual locks to be replaced when desired, it has been proposed to provide locks in which the barrels thereof are removable from the housing. In these arrangements, the barrel is retained in the housing by a tumbler that is in the form of a control tumbler. When eccentrically displaced under the action of a spring, this control tumbler projects outwardly from the substantially cylindrical barrel (so that the control tumbler is extended relative to the barrel) and collaborates with a stop or a shoulder (wall) defined by a groove formed in the housing for preventing the removal of the barrel from the housing. The shape of this control tumbler is such that when an appropriate tool or key is introduced, the control tumbler is returned into a centric position in which it no longer projects from the cylindrical barrel (so that the control tumbler is retracted relative to the barrel). The barrel may then be removed from the housing concommittantly with, and simply by the pulling of, the tool Thus removed, the barrel is able to be replaced by another barrel which then makes up a part of the combination of locks that use the common key.
Although the barrels of the independent locks are thereby permitted to be easily unlocked and/or replaced, as desired or needed, by other barrels that use the common key, this system can nonetheless be disadvantageous from a security viewpoint. Anyone equipped with an appropriate tool is, in the event that only one key is provided, able to both unlock and dislodge (remove) any of the barrels of any of the locks of this type of system. In the event that the system is of the type that utilizes a first common key for locking and unlocking functions and a second key for removal functions, then anyone equipped even with only an appropriate second key (which is often a key that has simplified contours and, as such, is readily susceptible to being counterfeited) is still able to dislodge and remove any of the barrels of the locks of the system, regardless whether the locks are locked or unlocked.
U.S. Pat. No. 2,061,456 issued to Falk attempts to solve these problems by providing a lock having a removable barrel with a control tumbler in which an extending end thereof is always extended relative to the barrel. The extending end has a pair of opposite rounded shoulders, so that the width of the extending end is reduced relative to the remainder of the control tumbler. When in the locking position, the extending end abuts a wall or shoulder formed in the barrel. In an unlocking position, the extending end coacts with slanted edges of a longitudinal slot, permitting removal of the barrel. In this fashion, the barrel can only be removed from the housing when the barrel is in the unlocked position.
U.S. Pat. No. 4,398,405 issued to Patriquin, attempts to solve these problems by providing a lock having a removable barrel equipped with a control tumbler that, in one position, has a first end extended, and a second end retracted, relative to the barrel. In another position, the first end is retracted, and the second end is extended, relative to the barrel. The extending end of the control tumbler is either the same width throughout its entire length or (like Falk '465) it is reduce din width relative to the remainder of the control tumbler. When an appropriate end is received in an annular groove so as to be aligned with a longitudinal slot, the barrel may be removed.
While each of the above disclosures is useful for its intended purposes, they also have several disadvantages. Among these are that in order to operate properly, at least one of each pair of matched longitudinal slots must terminate short of the annular groove while the other slot of the pair is in communication with the annular groove. Such an arrangement requires specialized tooling of the housing and/or the placement of specialized stops and inserts in the housing. This creates significant problems in manufacturing standardization and requires an increase in parts and inventories. Another disadvantage is the shape of the control tumblers. Because these tumblers are often fabricated from steel and brass while the barrels and housings are fabricated from a die cast zinc alloy, these parts are readily subject to deformation resulting from overpushing of the key, overpulling of the barrel, etc. Despite this, in the disclosures, the extending ends of the control tumblers (which is the portion of the control tumblers which subjects the barrel and the housing to the greatest amount of the stress) are either reduced in width, or at the most, are the same width throughout. Such an arrangement does nothing to spread the stress over as great an area an possible, so as to strengthen the said control tumbler and to reduce the likelihood of the deformation thereof.
Additionally, in Patriquin '405, to provide an appropriate annular groove, an arrangement is disclosed wherein the groove is open to the environment. Such a feature is not adaptable for use in locks having exterior applications, where it is exposed to the elements, such as snow, rain, etc., that can enter the internal workings thereof via the groove, damaging the workings of the lock. Also, the arrangements of Patriquin .varies.405 require that different types of control tumblers and longitudinal slots be utilized depending on whether the barrel of the lock is to be rotatable 90.degree., 180.degree., 360.degree., etc. This creates problems not only with manufacturing standardization, but also requires that a considerable inventory of parts, for the various tumblers, etc., of the locks be maintained.
Thus, it can be seen that there remains a need for a lock and a control tumbler therefor, in which the barrel is removable therefrom only when in the unlocked position, which is capable of being fabricated so that it does not present problems with manufacturing standardization and maintenance of parts inventory, and which provides an improved control tumbler that is capable of withstanding greater amounts of stress than those of the prior art.